I have read in a book written by a mystical visionary that Mary experienced all of the pain and suffering that Jesus experienced, from the scourging all the way to the painful expiration on the cross and that she was only preserved from death of this experience by a special grace. It is wonderful that Jesus had someone so close to him as to have shared this very part of his sufferings with him.
For our Protestant brothers and sisters calling out for a biblical foundation of the idea of the role of Mary as co-redemptrix, I can only offer yet another non-biblical source to appeal to you. I would like to quote the first page or so of St. Louis de Montfort’s book True Devotion to Mary:
"It was through the most holy Virgin Mary that Jesus came into the world, and it is also through her that He is to reign in the world.
Mary was singularly hidden during her life. It is on this account that the Holy Ghost and the Church call her Alma Mater–“Mother secret and hidden.” Her humility was so profound that she had no inclination on earth more powerful or more constant than that of hiding herself, from herself as well as from every other creature, so as to be known to God only.
He heard her prayers when she begged to be hidden, to be humbled and to be treated as in all respects poor and of no account. He took pleasure in hiding her from all human creatures, in her conception, in her birth, in her life, in her mysteries, and in her resurrection and Assumption. Even her parents did not know her, and the angels often asked one another: “Who is that?” (Cant. 3:6; 8:5) because the Most High either had hidden her from them, or if He did reveal anything, it was nothing compared to what he kept undisclosed.
God the Father consented that she should work no miracle, at least no public one, during her life, although He had given her the power to do so. God the Son consented that she should hardly ever speak, though He had communicated His wisdom to her. God the Holy Ghost, though she was His faithful spouse, consented that His Apostles and Evangelists should speak very little of her, and no more than was necessary to make Jesus Christ known."
Yet, much has been revealed about Mary in latter times according to God’s purpose as humanity comes to learn more.
So I would recommend books like The Glories of Mary, The Mystical City of God(look for the shorter abridged version too), and True Devotion to Mary to anyone. They can all be found at Tan Books:
www.tanbooks.com.